David Relman from Stanford University delivered a keynote address at this year’s American Society of Microbiology general meeting, during which he told attendees that the chances for successfully launching a project to study the entire human microbiome are becoming more promising.
“The Human Microbiome Project may become possible in the next year or two,” Relman said, pointing out that several pilot studies for specific regions of that microbiome are already underway. Among the more well-known have been studies of the microbial flora in the human gut and mouth. He also emphasized the importance of performing these studies to evaluate the normal, healthy state of these microbial communities rather than what they look like during illness. “We need to understand the state of health, not just disease,” he said.
Relman said that the ultimate goal of understanding the relationship between community gene content and gene expression could help scientists figure out cases where a group of microbes, rather than any single microbe, might be acting together as a pathogen, for example. He pointed out as well that so far, scientists have “a strong sense that each person’s genome sequence plays a significant role in the microbes and the volumes of microbes in each person.”
The person-to-person variability in microbial communities that supports that concept has been studied as early as birth, Relman said. He described a year-long project in his own lab in which researchers regularly sampled the microbes living in a baby’s intestinal tract for the first year of life. This was done for 14 babies and their parents, and results indicated that in the first two weeks chaos reigns in the baby’s gut, which at the time looks mostly like its mother’s. After that period, though, things become much more host-specific, he said; the only cases where there was not significant variation from one baby to the next was in a pair of twins, whose microbial flora were virtually indistinguishable from each other.
Going forward toward a more comprehensive whole-human microbiome project, Relman said, scientists will need to make strides in high-throughput microbial community analysis; linking genome-wide host-genotype patterns; single-cell analysis; and alternative cultivation techniques for microbes that can’t be cultured through current methods. With those advances, he contended, the scientific community would have a much stronger arsenal with which to study the patterns of microbial diversity associated with healthy states, the role of host genetics compared to the environment, and functional attributes of the microbiota, among others.
— Meredith Salisbury